update readme

README.md

@@ -59,7 +59,17 @@ For both the leaderboards, the winning teams will be required to publish their t
 
 # Evaluation
 
+As an evaluation metric, we are using the signal-to-distortion ratio (SDR), which is defined as,
 
+![](https://images.aicrowd.com/uploads/ckeditor/pictures/404/content_SDR_instr.png)
+
+where S𝑖𝑛𝑠𝑡𝑟(n) is the waveform of the ground truth and Ŝ𝑖𝑛𝑠𝑡𝑟(𝑛) denotes the waveform of the estimate. The higher the SDR score, the better the output of the system is.
+
+In order to rank systems, we will use the average SDR computed by
+
+![](https://images.aicrowd.com/uploads/ckeditor/pictures/405/content_SDR_song.png)
+
+for each song. Finally, the overall score is obtained by averaging SDRsong over all songs in the hidden test set.
 
 # Baselines
 
@@ -104,8 +114,8 @@ GitLab.
 
 ## FAQs
 
-* How do I submit a model?
-  * More information on submissions can be found at our [submission.md](/docs/submission.md). In short, you should push you code to the AIcrowd's gitlab with a specific git tag and the evaluation will be triggered automatically.
+### How do I submit a model?
+In short, you should push you code to the AIcrowd's gitlab with a specific git tag and the evaluation will be triggered automatically. More information on submissions can be found at our [submission.md](/docs/submission.md). 
 
 ### How do I specify my dependencies?